I have searched for this bug without finding it so I report it here:
When entering a nether portal, I spawned in Nether without a portal and inside netherrack, suffocating.
To reproduce, start a New world With seed -7348520253348302525.
Create a standard portal at -1008/16/106 facing west with portal socket in the floor (see image).
See second image for situation in Nether right after spawning.
This post is a duplicate of MC-57524.